Veytharion and Caltheris are amazing fights, both on Standard and on Cursed mode. Veytharion Cursed restricts you to a set number of healing pods per phase, and Caltheris gets a bigger health pool to compensate for extra DPS.
Starting with Paradox Junction, however, it feels like Treyarch is getting lazy with the balancing. Instead of coming up with meaningful gameplay changes, they just throw more mimics at you and remove armor drops. Totenreich has a similar issue, you literally get NO armor throughout the entire fight, and you get super sprinters for the entire duration of the fight instead of only phase 1 like in Standard. Armor drops are a critical part of survivability, especially since Armored and Heavy zombies(which spawn in large numbers during boss fights) can shred your armor in 2-3 hits, and in Totenreich's boss fight they can super sprint and ruin the small amount of armor you recovered via Golden Armor. This is compounded by the fact that you need to spin the box for usable weapons, since they ALSO started a trend in Paradox Junction where almost all of the wall weapons are nearly unusable for high rounds or bosses, which often means spending crucial rounds just getting a gun that's usable against the boss.